Messier 47

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Messier 47
Eso1441a.jpg
Observation data (J2000.0 epoch)
Right ascension 07h 36.6m[1]
Declination −14° 30′[1]
Distance 498 pc[1]
Apparent magnitude (V) 4.2
Apparent dimensions (V) 30.0′
Physical characteristics
Mass 453[1] M
Radius 10.61 pc[1]
Estimated age 78 million years
Other designations NGC 2422
See also: Open cluster, List of open clusters

Messier 47 (M47 or NGC 2422) is an open cluster in the constellation Puppis. It was discovered by Giovanni Batista Hodierna before 1654 and independently discovered by Charles Messier on February 19, 1771. It was later independently discovered again, under the current name NGC 2422.

There is actually no cluster in the position indicated by Messier, which he expressed in terms of its right ascension and declination with respect to the star 2 Puppis. However, if the signs of Messier's coordinate differences are changed, the position matches that of NGC 2422.[2] Until the equivalency of M47 with NGC 2422 was found, M47 was considered a lost Messier Object. The discovery that M47 and NGC 2422 were the same cluster only came in 1959 with a realization by Canadian astronomer T. F. Morris.[3]

M47 is at a distance of about 1,600 light-years from Earth with an estimated age of about 78 million years. The member stars of M47 have been measured down to about red dwarfs at apparent magnitude 19. There are around 500 members,[1] the brightest being HD 60855, a magnitude 5.7 Be star. The cluster is dominated by hot class B main sequence and giant stars, but a noticeable colour contrast comes from several bright red giants.[3]

M47 is located about a degree away from Messier 46, which is much older and much further away.[3]

References[edit]

  1. ^ a b c d e f Prisinzano, L; Micela, G; Sciortino, S; Favata, F (2003). "Luminosity and Mass Function of the Galactic open cluster NGC 2422". Astronomy & Astrophysics. 404 (3): 927. arXiv:astro-ph/0304321Freely accessible. Bibcode:2003A&A...404..927P. doi:10.1051/0004-6361:20030524. 
  2. ^ Houston, Walter Scott (2005). Deep-Sky Wonders. Sky Publishing Corporation. ISBN 1-931559-23-6. 
  3. ^ a b c "The hot blue stars of messier 47". ScienceDaily. 17 December 2014. 

External links[edit]

Coordinates: Sky map 07h 36.6m 00s, −14° 30′ 00″